Clinically relevant biomarkers in autism spectrum disorders and attention deficit hyperactivity disorder !

Autism spectrum disorders (ASD) and attention-deficit hyperactivity disorder (ADHD) are common and complex neurodevelopmental disorders. They are diagnosed based solely upon behavioral criteria with little to no consideration for potential biomedical underpinnings. Newer evidence, however, reveals that ASD is characterized by oxidative stress, decreased methylation capacity, limited production of glutathione, mitochondrial dysfunction, intestinal dysbiosis, increased toxic metal burden, immune dysregulation with a unique inflammatory bowel disease and immune activation of neuroglial cells, and ongoing brain hypoperfusion. Oxidative stress and immune dysregulation are also common features present in children with ADHD. These medical conditions have synergistically negative effects on development, cognition, focus, and attention. It is likely these biological abnormalities contribute significantly to the behavioral symptoms intrinsic in these disorders. Treatment for the underlying medical disorders is medically justified even if no clear immediate behavioral improvement is observed. In this article, we review the medical literature and discuss our clinical experience using various biomarkers for measuring oxidative stress, methylation capacity and transsulfuration, immune function, gastrointestinal problems, and toxic metal burden. These biomarkers are useful to guide the selection, efficacy, and sufficiency of biomedical interventions. The use of biomarkers is of greater importance in young children and individuals of any age with ASD, because they typically cannot adequately communicate regarding their symptoms.